Linear hydraulic valve

ABSTRACT

Examples are provided that describe a linear hydraulic valve. In one example a linear valve comprises a sleeve with a plurality of ports spaced apart from each other at a distance. The plurality of ports are associated with a plurality of pressurized fluids. A spool comprising a plurality of openings that correspond to the plurality of ports is provided within the sleeve. The plurality of openings are spaced apart in a manner that enables alignment of a given opening of the plurality of openings to a given port of the plurality of ports based on a given position of the spool within the sleeve. The linear valve comprises an actuator for moving the spool in a forward or reverse linear motion along a longitudinal axis of the sleeve. The spool may be moved to a given position based on selection of a pressurized fluid of the plurality of pressurized fluids.

CROSS REFERENCE TO RELATED APPLICATION

This U.S. patent application is a continuation of, and claims priorityunder 35 U.S.C. § 120 from, U.S. patent application Ser. No. 15/288,230,filed on Oct. 7, 2016, which is a continuation of U.S. patentapplication Ser. No. 14/587,873 filed on Dec. 31, 2014, which claimspriority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application62/027,577, filed on Jul. 22, 2014. The disclosures of these priorapplications are considered part of the disclosure of this applicationand are hereby incorporated by reference in their entireties.

GOVERNMENT LICENSE RIGHTS

This invention was made with government support under Contract No.W31P4Q-13-C-0107 awarded by the Defense Advanced Research ProjectsAgency. The government has certain rights in the invention.

TECHNICAL FIELD

This disclosure relates to linear hydraulic valves.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

One of the ways that hydraulic machines are capable of performing workis through use of pressurized fluids. Pressurized fluids may betransmitted throughout the machine to various hydraulic actuators.Hydraulic machinery has reached wide scale use due to the large powerthat can be transferred in the form of pressurized fluids and the largeavailability of actuators that can make use of the power.

Control is needed in order to operate hydraulic machinery in aneffective manner. As an example, one way control is provided is throughthe use of valves. The ability to select between various pressurizedfluids may be achieved through the use of a valve. This allows apassageway to be created that enables a pressurized fluid to flow from asource to an actuator that is responsible for moving a component of ahydraulic machine.

SUMMARY

In one example, a linear valve is provided comprising a sleeve. Thesleeve comprises a plurality of ports along a longitudinal axis andspaced apart from each other at a distance. The plurality of ports areassociated with a plurality of pressurized fluids. A spool is providedwithin the sleeve. The spool may be provided at a position of aplurality of positions within the sleeve. The spool comprises aninternal chamber. The spool comprises a plurality of openingscorresponding to the plurality of ports of the sleeve. The plurality ofopenings are spaced apart in a manner that enables alignment of a givenopening of the plurality of openings to a given port of the plurality ofports based on a given position of the spool within the sleeve.Alignment of the given opening to the give port provides access to theinternal chamber. The linear valve comprises an actuator for moving thespool in a forward or reverse linear motion along the longitudinal axisof the sleeve to positions of the plurality of positions within thesleeve. The given position is based on a selection of a pressurizedfluid of the plurality of pressurized fluids that corresponds to thegiven port so as to align the given opening of the plurality of openingswith the given port of the plurality of ports. The linear motion movesthe spool within the sleeve to cause transition between alignment ofopenings and corresponding ports. An amount of movement maps to a givenalignment.

In another example, a linear valve is provided comprising a sleeve. Thesleeve comprises a plurality of ports. The plurality of ports arepositioned along a longitudinal axis of the sleeve. The plurality ofports are spaced apart from each other at a first distance. A spool isprovided within the sleeve. The spool comprises a plurality of openingsthat form a plurality of channels. The plurality of openings arepositioned along a longitudinal axis of the spool. The plurality ofopenings are spaced apart from each other based on a second distance.The second distance is determined based on a fraction of the firstdistance. The linear valve comprises a sensor for determining a linearmovement of the spool based on a selection of a given pressurized fluidassociated with a given port of the plurality of ports of the sleeve. Amotor is coupled to the spool and configured for moving the spool alongthe longitudinal axis of the sleeve. The motor is configured for movingthe spool based on the linear movement to enable alignment between thegiven port of the plurality of ports and a given opening of theplurality of openings.

In another example, a linear valve is provided comprising a sleeve. Thesleeve comprises a plurality of ports. The plurality of ports arepositioned along a longitudinal axis of the sleeve. The plurality ofports are spaced apart from each other at a first distance. A spool isprovided within the sleeve. The spool comprises a plurality of openingsalong an external surface of the spool. The spool comprises an internalchamber. The plurality of openings are spaced apart from each other at asecond distance that is based on a fraction of the first distance. Theplurality of openings serve as a plurality of passageways from theexternal surface of the spool to the internal chamber. The plurality ofopenings comprises a plurality of grooves. The linear valve comprises alinear variable differential transformer for measuring a linear movementof the spool based on a selection of a given pressurized fluidassociated with a given port of the plurality of ports. The linear valvealso comprises a coupler for connecting the spool and the linearvariable differential transformer. A voice coil actuator is coupled tothe sleeve and configured for moving the spool along the longitudinalaxis of the sleeve based on the linear movement.

These as well as other aspects, advantages, and alternatives, willbecome apparent to those of ordinary skill in the art by reading thefollowing detailed description, with reference where appropriate to theaccompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A illustrates a side view of an example sleeve.

FIG. 1B illustrates a side view of an example spool.

FIG. 1C illustrates an exploded view of subcomponents of an examplelinear valve.

FIGS. 1D and 1E illustrate side views of another example linear valve.

FIGS. 2A-2C illustrate three different positions pertaining to anoperation of an example linear valve.

FIGS. 3A-3C illustrate three different positions pertaining to anoperation of another example linear valve.

FIG. 4A illustrates an exploded view of subcomponents of another examplelinear valve.

FIG. 4B illustrates a side view of an example sensor.

FIG. 5A illustrates a cross-sectional view of subcomponents of anexample linear valve inserted into a manifold block.

FIG. 5B illustrates a perspective view of the moving part of anotherexample linear valve.

FIG. 5C illustrates a cross-sectional view of an example linear valve.

FIG. 6 illustrates a cross-sectional view of another example linearvalve.

DETAILED DESCRIPTION

The following detailed description describes various features andfunctions of the disclosed systems and methods with reference to theaccompanying figures. In the figures, similar symbols identify similarcomponents, unless context dictates otherwise. The illustrative systemand method embodiments described herein are not meant to be limiting. Itmay be readily understood that certain aspects of the disclosed systemsand methods can be arranged and combined in a wide variety of differentconfigurations, all of which are contemplated herein.

Examples described herein include subsystems that enable a hydraulicmachine, including a linear valve, to enable selection of a pressurizedfluid. The linear valve may include a sleeve comprising a plurality ofports spaced apart from each other at a distance. By way of example, theplurality of ports may be spaced along the long axis of the sleeve. Theplurality of ports may be associated with a plurality of pressurizedfluids. In one example, the plurality of ports may be associated withfour pressurized fluids that correspond to four different levels ofpressure. The linear valve may also include a spool that is providedwithin the sleeve. The spool may be positioned at a position of aplurality of positions within the sleeve. The spool may comprise aplurality of openings that are spaced apart in a manner that enablesalignment of a given opening of the plurality of openings to a givenport of the plurality of ports based on a given position of the spoolwithin the sleeve. The linear valve may also include an actuator formoving the spool in a forward or reverse linear motion along alongitudinal axis of the sleeve to positions of the plurality ofpositions within the sleeve. The given position may be based on aselection of a pressurized fluid of the plurality of pressurized fluidsthat corresponds to the given port so as to align the given opening ofthe plurality of openings with the given port of the plurality of ports.The linear motion may be provided to move the spool within the sleeve tocause transition between alignment of openings and corresponding ports,wherein an amount of movement maps to a given alignment.

Referring now to the figures, FIG. 1A illustrates a side view of asleeve 102. The sleeve 102 comprises a plurality of ports 104 a and 104b, a plurality of control port holes 106 a and 106 b, an internalcylindrical passage 108, and an undercut 109.

In one example, the sleeve 102 may comprise any number of materials suchas aluminum, steel, and stainless steel. In one example, the sleeve 102may comprise a total height of about 60 mm with an outside diameter ofabout 36 mm. By way of example, the sleeve 102 may comprise an internaldiameter of about 9 mm for receiving an example spool with a diameter ofabout 9 mm. Maintaining a minimal amount of separation between thesleeve 102 and the example spool may help to reduce leakage associatedwith the plurality of pressurized fluids.

The plurality of ports 104 a and 104 b are spaced apart from each otherat a distance. In one example, the distance associated with the spacingof the plurality of ports 104 a and 104 b is about 5.75 mm. Theplurality of ports 104 a and 104 b may have an axial width of about 3 mmand an axial height of about 0.45 mm. The plurality of ports 104 a and104 b are associated with a plurality of pressurized fluids. In oneexample, the plurality of ports 104 a and 104 b may comprise five ports,and the pressure levels associated with the five ports may comprisepressurized fluids at 3000 psi, 2250 psi, 1500 psi, 750 psi, and 100psi. In this example, a hydraulic machine may be configured to operatein a dynamic environment that requires the use of various pressurelevels associated with the plurality of pressurized fluids.

As shown in FIG. 1A, the plurality of control port holes 106 a and 106 bare positioned about an external surface of the sleeve 102. Theplurality of control port holes 106 a and 106 b may be configured toreceive a pressurized fluid with a pressure level that corresponds to aselection of a pressurized fluid corresponding to a given port of theplurality of ports 104 a and 104 b. By way of example, the plurality ofcontrol port holes 106 a and 106 b may be configured to receive ordischarge a pressurized fluid to or from a given port of the pluralityof ports 104 a and 104 b.

Depending on the pressurized fluid selected with the given port of theplurality of ports 104 a and 104 b, a given flow force associated withthe pressurized fluid may cause an unintended movement of an examplespool within the sleeve 102. Within examples, the plurality of ports maybe spaced symmetrically about a circumference of the sleeve to mitigateany undesirable pressure or flow induced radial forces. In one example,the plurality of control port holes 106 a and 106 b may comprise adiameter of about 1.8 mm.

In another example, the sleeve 102 may comprise an internal cylindricalpassage 108 comprising a diameter of about 9 mm. The internalcylindrical passage 108 may be configured to receive a sliding member.By way of example, the internal cylindrical passage 108 may be coatedwith a material such as diamond-like carbon to reduce friction and wearbetween the sliding member and the internal cylindrical passage 108.

Referring to FIG. 1A, the sleeve 102 may comprise an undercut 109. Theundercut 109 may be an annular undercut within the sleeve 102 thatprovides access to the plurality of control port holes 106 a and 106 b.By way of example, the undercut 109 may provide access to a plurality ofcontrol openings of a spool (not shown) as well.

FIG. 1B illustrates a side view of a spool 110. The spool 110 comprisesa plurality of openings 112 a and 112 b. The spool 110 comprises aplurality of grooves 114 a and 114 b within the plurality of openings112 a and 112 b. The spool 110 also comprises a plurality of controlopenings 116 a and 116 b along an external surface of the spool 110. Theplurality of control openings 116 a and 116 b are configured tocommunicate with an internal chamber 113 of the spool 110.

In one example, the spool 110 may be provided within the sleeve 102. Thespool 110 may be configured to move in a linear motion within theinternal cylindrical passage 108 in order to provide the spool 110 at aposition of a plurality of positions within the sleeve 102. In anotherexample, the spool 110 may comprise a length of about 47.5 mm and adiameter of 9 mm. The spool 110 may comprise any number of materialssuch as aluminum, steel, and stainless steel.

The plurality of openings 112 a and 112 b may be spaced apart from eachother at substantially an equal distance. In one example, the pluralityof grooves 114 a and 114 b may comprise a width of about 0.5 mm and beseparated at a distance of about 4.75 mm. In another example, dependingon the position of the plurality of positions of the spool 110 withinthe sleeve 102, a given groove of the plurality of grooves 114 a and 114b may be configured to align with a given port of the plurality of ports104 a and 104 b. An alignment between the given groove and the givenport would allow the pressurized fluid to flow to and from the sleeve102 to the spool 110.

As shown in FIG. 1B, the spool 110 may comprise the internal chamber113. The internal chamber 113 may be configured to receive a pluralityof pressurized fluids. By way of example, the internal chamber 113 maybe accessed through the plurality of grooves 114 a and 114 b.

The plurality of grooves 114 a and 114 b of the spool 110 may correspondto the plurality of ports 104 a and 104 b of the sleeve 102. Theplurality of openings 112 a and 112 b may be spaced apart in a mannerthat enables alignment of a given opening of the plurality of openings112 a and 112 b to a given port of the plurality of ports 104 a and 104b based on a given position of the spool 110 within the sleeve 102. Theplurality of openings 112 a and 112 b are configured as through-holeswhich break through to the internal chamber 113, thus connecting to theplurality of control openings 116 a and 116 b in the spool 110. In oneexample, the plurality of openings 112 a and 112 b may bepressure-balanced. For example, in order to be pressure-balanced theplurality of openings 112 a and 112 b at a given position may include acircular array of two holes that are spaced 180° apart. In anotherexample, the plurality of openings 112 a and 112 b at a given positionmay include a circular array of three holes that are spaced 120° apart.In one example, based on the given position of the spool 110 within thesleeve 102, the given position may allow the pressurized fluidassociated with the given port to flow from the sleeve 102 through theplurality of openings 112 a and 112 b into the internal chamber 113 andout of the plurality of control openings 116 a and 116 b.

As shown in FIG. 1B, the spool 110 may comprise a plurality of controlopenings 116 a and 116 b configured as through-holes connecting to theinternal chamber 113 in order to enable a flow of the plurality ofpressurized fluids. In one example, the plurality of control openings116 a and 116 b may be spaced symmetrically about a circumference of thespool 110 to mitigate any undesirable pressure or flow induced radialforces.

FIG. 1C illustrates an exploded view of subcomponents of an examplelinear valve 100. The linear valve 100 comprises an actuator 118 coupledto the spool 110. The sleeve 102 is configured to receive the spool 110.

The actuator 118 may be configured for moving the spool 110 in a forwardor reverse linear motion along a longitudinal axis 120 of the sleeve 102to positions of the plurality of positions within the sleeve 102. Thegiven position of the plurality of positions is based on a selection ofa pressurized fluid of the plurality of pressurized fluids. Theselection of the pressurized fluid of the plurality of pressurizedfluids corresponds to the given port so as to align the given opening ofthe plurality openings 114 a and 114 b with the given port of theplurality of ports 104 a and 104 b. The linear motion is determined formoving the spool 110 within the sleeve 102 to cause a transition betweenalignment of openings 114 a and 114 b and corresponding ports 104 a and104 b. In one example, an amount of movement of linear motion maps to agiven alignment.

In another example, the actuator 118 may comprise a voice coil actuator.By way of example, the voice coil actuator may comprise a coil assemblyand a stator assembly. The coil assembly may include a bobbin and thecoil. The stator assembly may include an outer shell and an inner shellas well as permanent magnet material which may produce a radial magneticflux in the annular gap between the two shells. The coil assembly may beinserted into an annular gap, and current may be supplied to the coil toproduce a force tending to push or pull the bobbin into or out of thestator assembly. Various types of actuators may be implemented toprovide the forward or reverse linear motion such as a DC brush motor,DC brushless motor, or a stepper motor just to name a few.

The forward or reverse linear motion enables the spool 110 to move ineither direction, and to couple to a given first port at a firstinstance, and then to move in either direction so as to couple to agiven second port using a predetermined amount of movement. Thepredetermined amount of movement may refer to an amount of movement ofthe spool 110 in either direction to cause alignment to a subsequentport based on a difference in distance between the spacing of twoneighboring ports of the plurality of ports and the spacing of twoneighboring openings of the plurality of openings. Using this exampleconfiguration, depending on a level or a pressurized fluid coupled to agiven port of the sleeve 102, the valve can enable transitioning from ahigh pressure to a low pressure in a short amount of time. In an examplewhere the valve controls fluid for operating actuators or a movingrobotic device, the valve may provide a high pressurized fluid for fastwalking, and quickly switch to a low pressurized fluid using the forwardor reverse linear motion (e.g., when a high and low pressurized fluidare mapped to first and second ports of the sleeve) to transition to aport associated with the low pressurized fluid to cause the device toslow down quickly.

The spool 110 is provided within the sleeve 102 in order to enablealignment between the given opening of the spool 110 and the given portof the sleeve 102. An optimal distance associated with a movement oftravel of the spool 110 within the sleeve 102 may be determined in orderto enable a fast transition between alignment of the plurality ofopenings and the plurality of ports. A faster speed corresponding tochanging an alignment of the plurality of openings 114 and the pluralityof ports 104 a and 104 b may permit a hydraulic machine associated withthe linear valve 100 to operate in an environment that requires a fasttransition between the plurality of forces associated with the pluralityof pressurized fluids.

The sleeve 102 is configured to receive the spool 110 in order to enableselection of a given pressurized fluid of the plurality of pressurizedfluids. By way of example, the sleeve 102 may comprise a radialclearance of about 2 to 4.5 microns between the cylindrical passage 108and the spool 110. The radial clearance of about 2 to 4.5 microns wouldallow the spool 110 to operate based on any radial expansion orcontraction associated with the pressure level of the given pressurizedfluid while exhibiting reasonable levels of leakage and viscous frictionwhile using typical hydraulic fluids at typical temperatures.

FIGS. 1D and 1E illustrate side views of a portion of the linear valve100. The spool 110 is provided within the cylindrical passage 108 of thesleeve 102. An example alignment between a given opening 115 of theplurality of openings 114 a and 114 b and a given port 105 of theplurality of ports 104 a and 104 b is shown in FIGS. 1D and 1E.

Referring to FIG. 1D, the spool 110 is provided at a given positionwithin the cylindrical passage 108 in order to cause alignment betweenthe given opening 115 of the plurality of openings 114 a and 114 b and agiven port 105 of the plurality of ports 104 a and 104 b, and therebyallow a pressurized fluid to flow from the sleeve 102 and through thespool 110. In one example, the actuator 118 may be configured to movethe spool 110 to the given position so that the given opening 115 of theplurality of openings 114 a and 114 b overlaps the given port 105 of theplurality of ports 104 a and 104 b in order to enable substantially fullalignment between the given opening 115 and the given port 105. Enablingsubstantially full alignment allows the pressurized fluid to flow at amaximum flow rate associated with the given port 105.

Referring to FIG. 1E, the spool 110 is provided at a given positionwithin the cylindrical passage 108 in order to cause alignment betweenthe given opening 115 of the plurality of openings 114 a and 114 b and agiven port 105 of the plurality of ports 104 a and 104 b, and therebyallow a pressurized fluid to flow from the sleeve 102 and through thespool 110. In one example, the actuator 118 may be configured to movethe spool 110 to the given position so that the given opening 115 of theplurality of openings 114 a and 114 b partially overlaps the given port105 of the plurality of ports 104 a and 104 b for metering of thepressurized fluid. Metering the pressurized fluid may allow for a smoothchange in pressure levels associated with a subcomponent of an examplehydraulic machine. Metering of the pressurized fluid may be used forsmoothly reducing flow or pressure to an actuator to control theactuator's force or velocity.

FIGS. 2A-2C illustrate three different positions of a spool within asleeve pertaining to an example operation of a linear valve 200. Asleeve 202 comprising a plurality of ports 203, 204, 205, and 206 isshown in FIG. 2A. The sleeve 202 also comprises a control port 207. Aspool 208 comprising a plurality of openings 209, 210, 211, and 212 isincluded in the sleeve 202. The sleeve 202 also comprises a controlopening 213.

Referring to FIG. 2A, the spool 208 is positioned at a first position215 within the sleeve 202 causing a given port 203 to substantiallyalign to a given opening 209. As shown in FIG. 2A, ports 204, 205, and206 are not aligned to openings 210, 211, and 212 while alignment occursbetween the given port 203 and the given opening 209. Alignment betweenthe given port 203 and the given opening 209 prevents the plurality ofpressurized fluids associated with ports 204, 205, and 206 from beingselected while the spool 208 is positioned at the first position 215.

Referring to FIG. 2B, the spool 208 is positioned at a second position217 within the sleeve 202 causing a given port 204 to substantiallyalign to a given opening 210. As shown in FIG. 2B, ports 203, 205, and206 are not aligned to openings 209, 211, and 212 while alignment occursbetween the given port 204 and the given opening 210. Alignment betweenthe given port 204 and the given opening 210 prevents the plurality ofpressurized fluids associated with ports 203, 205, and 206 from beingselected while the spool 208 is positioned at the second position 217.

Referring to FIG. 2C, the spool 208 is positioned at a third position219 within the sleeve 202 causing a given port 205 to substantiallyalign to a given opening 211. As is shown in FIG. 2B, ports 203, 204,and 206 are not aligned to openings 209, 210, and 212 while alignmentoccurs between the given port 205 and the given opening 211. Alignmentbetween the given port 205 and the given opening 211 prevents theplurality of pressurized fluids associated with ports 203, 204, and 206from being selected while the spool 208 is positioned at the thirdposition 219.

In one example, the plurality of ports 203, 204, 205, and 206 have axialwidths of substantially equal lengths as shown in FIGS. 2A-2C. Inanother example, the plurality of openings 209, 210, 211, and 212 havewidths of substantially the same lengths as the axial widths of theplurality of ports 203, 204, 205, and 206.

FIGS. 3A-3C illustrate three different positions of a spool within asleeve pertaining to an operation of a linear valve 300. A sleeve 302comprising a plurality of ports 303, 304, 305, and 306 is shown in FIG.3A. The sleeve 302 also comprises a control port 307. A spool 308comprising a plurality of openings 309, 310, 311, and 312 is shown inFIG. 3A. The sleeve 302 also comprises a control opening 313.

Referring to FIG. 3A, the spool 308 is positioned at a first position315 within the sleeve 302 causing a given port 304 to partially overlapa given opening 310. As is shown in FIG. 3A, ports 303, 305, and 306 arenot aligned to openings 309, 311, and 312 while alignment occurs betweenthe given port 304 and the given opening 310. Alignment between thegiven port 304 and the given opening 310 prevents the plurality ofpressurized fluids associated with ports 303, 305, and 306 from beingselected while the spool 308 is positioned at the first position 315.Since the given port 304 partially overlaps the given opening 310, onlya metered amount of the pressurized fluid associated with the given port304 will flow. Metering the pressurized fluid provides an additionallevel of control over a flow rate associated with the pressurized fluid.

Referring to FIG. 3B, the spool 308 is positioned at a second position317 within the sleeve 302 causing a given port 305 to partially overlapa given opening 311. As is shown in FIG. 3B, ports 303, 304, and 306 arenot aligned to openings 309, 310, and 312 while alignment occurs betweenthe given port 305 and the given opening 311. Alignment between thegiven port 305 and the given opening 311 prevents the plurality ofpressurized fluids associated with ports 303, 304, and 306 from beingselected while the spool 308 is positioned at the second position 317.

Referring to FIG. 3C, the spool 308 is positioned at a third position319 within the sleeve 302 causing a given port 306 to partially overlapa given opening 312. As is shown in FIG. 3B, ports 303, 304, and 305 arenot aligned to openings 309, 310, and 311 while alignment occurs betweenthe given port 306 and the given opening 312. Alignment between thegiven port 306 and the given opening 312 prevents the plurality ofpressurized fluids associated with ports 303, 304, and 305 from beingselected while the spool 308 is positioned at the third position 319.

In one example, the plurality of ports 303, 304, 305, and 306 have axialwidths of unequal lengths as shown in FIGS. 3A-3C. In another example,the plurality of openings 309, 310, 311, and 312 have widths of unequallengths that correspond to the axial widths of the plurality of ports303, 304, 305, and 306 as shown in FIGS. 3A-3C.

FIG. 4A illustrates an exploded view of subcomponents of another examplelinear valve 400. Referring to FIG. 4A, linear valve 400 comprises asleeve 402. A spool 404 is provided within the sleeve 402. A controller406 may be coupled to the sleeve 402. A linear motor 408 coupled to thespool 404 is shown in FIG. 4A.

The sleeve 402 comprises a plurality of ports 410 a and 410 b. Theplurality of ports 410 a and 410 b are positioned along a longitudinalaxis 412 of the sleeve 402. The plurality of ports 410 are spaced apartfrom each other at a first distance.

The spool 404 comprises a plurality of openings 414 a and 414 b. Theplurality of openings 414 a and 414 b may be machined through the spool404 in order to form a plurality of channels. The plurality of openings414 a and 414 b may each comprise grooves, slots or holes connectingthrough the wall of spool 404 to an internal chamber 413. The pluralityof openings 414 a and 414 b are positioned along a longitudinal axis 416of the spool 404. In one example, the plurality of openings 414 a and414 b are spaced apart from each other based on a second distance. Thesecond distance may be determined based on a fraction of the firstdistance.

In one example, the fraction may be less than one. By way of example,the second distance and the first distance may differ by a givenfraction such that only a given port and corresponding given opening arealigned at a given position. In this example, the alignment may occur insequence as the spool 404 traverses its travel.

In another example, the fraction may be greater than one. In thisexample, the larger of either the first distance or the second distancemay be associated with either the plurality of openings 414 a and 414 bor the plurality of ports 410 a and 410 b. By way of example, the seconddistance could be sixth-fifths of the first distance and enable properoperation of the linear valve 400.

The relationship between the first distance and the second distanceenables the spool 404 to be positioned within the sleeve 402 based on apredetermined distance. The relationship of the first distance to thesecond distance enables a given port to correspond to a given opening asthe spool 404 is positioned within the sleeve 402. In one example, apredetermined linear movement is used to move the spool 404 within thesleeve 402 to provide alignment between the plurality of openings 414 aand 414 b and the plurality of ports 410 a and 410 b. By way of example,the predetermined linear movement may be configured to cause alignmentbetween a given opening 415 and a given port 411 in a similar manner toa movement between a Vernier scale and a fixed main scale.

The linear motor 408 may be configured for moving the spool 404 alongthe longitudinal axis 412 of the sleeve 402 based on the linear movementto enable alignment between the given port of the plurality of ports 410a and 410 b and a given opening of the plurality of openings 414 a and414 b. In one example, the motor 408 may comprise a brushed permanentmagnet DC motor or a brushless AC motor.

Referring to FIG. 4A, the sensor 406 is configured for determining alinear movement of the spool 404 based on a selection of a givenpressurized fluid associated with a given port of the plurality of ports410 a and 410 b of the sleeve 402. In one example, the sensor 406 maycomprise a linear encoder that is configured to provide accuratemeasurement within 1 or 2 microns of a position of the spool 404 withinthe sleeve 402.

FIG. 4B illustrates a side view of the example sensor 406. In oneexample, the sensor 406 may comprise a linear variable differentialtransformer 418. By way of example, dimensions associated with a tubularpart 419 and a plunger (not shown) may be altered as necessary so thatthe overall length of the linear variable differential transformer 418is reduced based on a desired stroke length associated with the movementof the spool 404. For example, the tubular part 419 may be anchored tothe sleeve 402 and the plunger attached to the spool 404. In anotherexample, the linear variable differential transformer 418 may be coupledto the motor 408.

FIG. 5A illustrates a cross-sectional view of subcomponents of anotherexample linear valve inserted into a manifold block. A sleeve 502comprising a plurality of ports 504 a and 504 b is provided within amanifold 500 is shown in FIG. 5A. A spool 506 comprising a plurality ofopenings 508 a and 508 b is provided within the sleeve 502.

Referring to FIG. 5A, the plurality of ports 504 a and 504 b arepositioned along a longitudinal axis 501 of the sleeve 502. Theplurality of ports 504 a and 504 b are spaced apart from each other at afirst distance 505. By way of example, the first distance 505 may beabout 5.75 mm. In one example, the plurality of ports 504 a and 504 bhave widths 515 of substantially equal lengths as shown in FIG. 5A.

The spool 506 comprises a plurality of openings 508 a and 508 b along anexternal surface of the spool 506. The plurality of openings 508 a and508 b comprise a plurality of grooves 510 a and 510 b configured asthrough-holes. The plurality of grooves 510 a and 510 b are spaced apartfrom each other at a second distance 509. By way of example, the seconddistance 509 may be about 4.75 mm. In this example, the second distance509 is less than the first distance 505 in order to enable alignmentbetween a given groove of the plurality of grooves 510 a and 510 b and agiven port of the plurality of ports 504 a and 504 b based on a givenposition of the spool 506 within the sleeve 502. In one example, theplurality of grooves 510 a and 510 b have widths 516 of substantiallythe same lengths as the widths 515 of the plurality of ports 504 a and504 b as shown in FIG. 5A. Other examples are possible as well, anddimensions provided herein are for illustration only.

In one example, the second distance 509 is a fraction of the firstdistance 505. The second distance 509 may be determined based on afraction of the first distance 505 that enables a given port of theplurality of ports 504 a and 504 b to align with a given groove of theplurality of grooves 510 a and 510 b one at a time. In another example,a linear movement based on a predetermined distance, wherein thepredetermined distance corresponds to a difference between the firstdistance 505 and the second distance 509, enables a transition inalignment between the plurality of ports 504 a and 504 b and theplurality of grooves 510 a and 510 b. By way of example, a selection ofthe plurality of pressurized fluids associated with the plurality ofports 504 a and 504 b may be made in a fast manner due to thepredetermined distance required to transition alignment between theplurality of ports 504 a and 504 b and the plurality of grooves 510 aand 510 b.

As shown in FIG. 5A, the sleeve 502 comprises a plurality of seals 503 aand 503 b. The plurality of seals 503 a and 503 b and seal sleeve 502create a plurality of annular channels 512 a and 512 b associated with aplurality of pressurized fluids. By way of example, the plurality ofseals 503 a and 503 b may comprise a plurality of double-V typehydraulic seals. The plurality of double-V type hydraulic seals wouldwork in a similar manner to an O-ring seal.

Referring to FIG. 5A, annular channel 514 connects to control port 513.The control port 513 comprises control port holes 507 a and 507 b andundercut groove 511. The undercut groove 511 communicates with controlopening 517 which provides access to internal chamber 519 of the spool506.

FIG. 5B illustrates a perspective view of the moving part of an examplelinear valve. The spool 506 is coupled to a coupler 532. The coupler 532is shown coupled to a voice coil assembly 528 which includes a bobbin527 and a coil 529. The spool 506 is also coupled to the plunger 533 bymeans of the coupler 532.

The coupler 532 may be configured to have a length of about 26 mm. Inone example, the coupler 532 may be configured to receive a plurality ofpins 538 a and 538 b coupled to an external surface of the coupler 532.The coupler 532 may comprise vent holes 531 a and 531 b that minimizefluid forces due to displacement of fluid as the voice coil assembly 528extends or retracts. In one example, the coupler 532 may be fabricatedout of an aluminum alloy. Any number of other materials may be used tofabricate the coupler 532.

Referring to FIG. 5B, the voice coil assembly 528 comprises the bobbin527 and the coil 529. In one example, the voice coil assembly 528 maycomprise a plurality of holes 530 a and 530 b for coupling to thecoupler 532 through the use of a plurality of fasteners. By way ofexample, the plurality of pins 538 a and 538 b may be anti-rotation pinsin order to prevent wires on the voice coil assembly from twisting.

FIG. 5C illustrates a cross-sectional view of an example linear valve500. Referring to FIG. 5C, the spool 506 is provided within the sleeve502. The spool 506 is coupled to the coupler 532. The coupler 532 isalso coupled to the voice coil assembly 528. The voice coil actuatorstator 518 is configured to receive the voice coil assembly 528 as wellas the linear variable differential transformer 524. A top cap 534 iscoupled to the sleeve 502. A bottom cap 536 is coupled to the top cap534.

Referring to FIG. 5C, the spool 506 is shown at a given position withinthe sleeve 502. Based on the given position of the spool 506, the spool506 is shown to be in a null position. While the spool 506 is in thenull position, none of the ports of the plurality of ports 504 a and 504b are aligned with the grooves of the plurality of grooves 510 a and 510b and control port 513 is closed off from the plurality of pressurizedfluids.

The coupler 532 may comprise a plurality of pins 538 a and 538 b coupledto an external surface of the coupler 532. A given pin of the pluralityof pins 538 a and 538 b may comprise steel and have a length of about 8mm. By way of example, the plurality of pins 538 a and 538 b may engageslots to limit rotation of the voice coil assembly and thus prevent theterminal wires of the voice coil from getting tangled. As shown in FIG.5C, the coupler 532 may comprise vent holes 531 a and 531 b allowing thevoice coil actuator to operate when flooded with a fluid. In oneexample, the coupler 532 may be connected to the spool 506.

The sleeve 502 may comprise a plurality of slots 540. By way of example,the plurality of slots 540 may be machined into the sleeve andconfigured for receiving the plurality of pins 538 a and 538 b.Referring to FIG. 5C, the spool 506 may be insensitive to rotaryposition due to the plurality of grooves 508 being circumferential.

In one example, it may be important to prevent unintentional rotation ofthe spool 506 within the sleeve 502. In this example, to prevent radialimbalance between the spool 506 and the sleeve 502 the use ofcircumferential grooves may be used. In another example, the pluralityof pins 538 a and 538 b may be provided within the plurality of slots540 and may serve to reduce an unintentional rotation of the spool 506within the sleeve 502. By way of example, the plurality of pins 538 aand 538 b may be anti-rotation pins that help to avoid twisting ofvoice-coil leads.

The linear variable differential transformer 524 is provided within thevoice coil actuator stator 518. In one example, the linear variabledifferential transformer 524 is configured for measuring a linearmovement of the spool 506 based on a selection of the given pressurizedfluid associated with the given port of the plurality of ports 504 a and504 b. The linear movement enables alignment between the given port ofthe plurality of ports 504 a and 504 b and a given opening of theplurality of openings 508 a and 508 b. In one example, the linearvariable differential transformer 524 may be connected to the voice coilactuator stator 518.

The voice coil actuator stator 518 may be coupled to the sleeve 502 andconfigured for moving the spool 506 along the longitudinal axis 501 ofthe sleeve 502. The voice coil actuator stator 518 may be configured formoving the spool 506 based on the linear movement measured by the linearvariable differential transformer 524.

In one example, the top cap 534 may comprise aluminum and have adiameter of about 49 mm. The top cap 534 may be coupled to the sleeve502 and configured to provide a housing to various subcomponents of thelinear valve 500 so that a given contaminant does not reach the varioussubcomponents.

The bottom cap 536 may be configured for attaching to the top cap 534and also configured for preventing the given contaminant from reachingthe various subcomponents. In one example, the bottom cap 536 maycomprise aluminum and have a diameter of about 49 mm.

FIG. 6 illustrates a cross-sectional view of another example linearvalve 600. The linear valve 600 is coupled to a plurality of pressurerails 602, 604, 606, 608, and 610. The linear valve 600 is also coupledto a hydraulic cylinder 614.

As shown in FIG. 6, the linear valve 600 is coupled to the plurality ofpressure rails 602, 604, 606, 608, and 610. The plurality of pressurerails 602, 604, 606, 608, and 610 may be configured to provide aplurality of pressurized fluids at various pressure levels. In oneexample, the pressure levels associated with the plurality of pressurerails 602, 604, 606, 608, and 610 may comprise pressurized fluids at3000 psi, 2250 psi, 1500 psi, 750 psi, and 100 psi. In another example,a given pressurized fluid of the plurality of pressurized fluids may beselected depending on a need to provide a given amount force to thehydraulic cylinder 614.

Referring to FIG. 6, the linear valve 600 may be coupled to thehydraulic cylinder 614 through a fluid line 612. Based on a selection ofa given pressurized fluid of the plurality of pressurized fluids, thelinear valve 600 may enable the given pressurized fluid to flow throughthe linear valve 600 to the hydraulic cylinder 614 in order to cause agiven force based on a given pressure level associated with the givenpressurized fluid to allow extension or retraction of the hydrauliccylinder 614.

By way of example, a signal corresponding to a selection of the givenpressurized fluid may be received within a controller. The controllermay be configured to determine the linear movement necessary to enableselection of the given pressurized fluid based on information indicatinga position of a spool within a sleeve that may be received from anexemplary encoder. In this example, the controller may be configured toprovide a signal corresponding to the required linear movement to amotor in order to position the spool within the sleeve and enableselection of the given pressurized fluid.

It should be understood that arrangements described herein are forpurposes of example only. As such, those skilled in the art willappreciate that other arrangements and other elements (e.g. machines,interfaces, functions, orders, and groupings of functions, etc.) can beused instead, and some elements may be omitted altogether according tothe desired results. Further, many of the elements that are describedare functional entities that may be implemented as discrete ordistributed components or in conjunction with other components, in anysuitable combination and location, or other structural elementsdescribed as independent structures may be combined.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopebeing indicated by the following claims, along with the full scope ofequivalents to which such claims are entitled. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting.

What is claimed is:
 1. A linear valve comprising: a sleeve defining: aplurality of fluid ports arranged about the sleeve, each fluid portassociated with a respective fluid pressure; and a control port in fluidcommunication with the plurality of fluid ports; a spool movablydisposed within the sleeve for movement between a plurality of positionswithin the sleeve, the spool defining: a plurality of openingscorresponding with the plurality of fluid ports of the sleeve andarranged about the spool to enable selective alignment of a givenopening of the plurality of openings with a given fluid port of theplurality of fluid ports at a given position of the plurality ofpositions; and a control opening in fluid communication with theplurality of openings; and an actuator configured to move the spoolalong a linear movement to the given position of the plurality ofpositions within the sleeve based on a selection of the respective fluidpressure associated with the given fluid port of the plurality of fluidports of the sleeve, wherein the selective alignment of the givenopening with the given fluid port at the given position allows flow of apressurized fluid at the respective fluid pressure associated with thegiven fluid port through the control opening to the control port.
 2. Thelinear valve of claim 1, wherein the actuator is configured to move thespool to the given position so that the given opening of the pluralityof openings partially overlaps the given fluid port of the plurality offluid ports for metering of the pressurized fluid.
 3. The linear valveof claim 1, wherein the actuator is configured to move the spool to thegiven position so that the given opening of the plurality of openingsoverlaps the given fluid port of the plurality of fluid ports in orderto enable substantially full alignment between the given opening and thegiven fluid port.
 4. The linear valve of claim 1, wherein the pluralityof openings are configured as through-holes in the spool and arepressure-balanced.
 5. The linear valve of claim 1, wherein the pluralityof fluid ports have axial widths of substantially equal lengths.
 6. Thelinear valve of claim 5, wherein the plurality of openings have widthsof substantially the same lengths as the axial widths of the pluralityof fluid ports.
 7. The linear valve of claim 1, wherein the plurality offluid ports have axial widths of unequal lengths.
 8. The linear valve ofclaim 7, wherein the plurality of openings have widths of unequallengths that correspond to the axial widths of the plurality of fluidports.
 9. The linear valve of claim 1, wherein the sleeve defines afirst longitudinal axis and the plurality of ports are spaced apart fromeach other along the longitudinal axis of the sleeve at a firstdistance, and wherein the spool defines a second longitudinal axis andthe plurality of openings are spaced apart from each other along thelongitudinal axis of the spool based on a second distance, the seconddistance based on a fraction of the first distance.
 10. A linear valvecomprising: a sleeve defining: a plurality of fluid ports arranged aboutthe sleeve, each fluid port associated with a fluid pressure; and acontrol port in fluid communication with the plurality of fluid ports; aspool movably disposed within the sleeve for movement between aplurality of positions, the spool defining: a plurality of openingscorresponding with the plurality of fluid ports of the sleeve andarranged about the spool to enable selective alignment of a givenopening of the plurality of openings with a given fluid port of theplurality of fluid ports at a given position of the plurality ofpositions; and a control opening in fluid communication with theplurality of openings; an actuator configured to move the spool in alinear movement between the plurality of positions within the sleeve,wherein the selective alignment of the given opening with the givenfluid port at the given position allows flow of a pressurized fluid atthe fluid pressure associated with the given fluid port through thecontrol opening to the control port; a sensor for determining a positionof the spool within the sleeve; and a controller for determining thelinear movement of the spool based on the position of the spool withinthe sleeve and a selection of a given fluid pressure associated with thegiven fluid port of the plurality of fluid ports of the sleeve.
 11. Amethod comprising: receiving, at a controller, an indication of aselected fluid pressure; and actuating, by the controller, an actuatorto move a spool movably disposed within a sleeve along a linear movementto a given position of a plurality of positions based on the selectedfluid pressure, wherein the sleeve defines: a plurality of fluid portsarranged about the sleeve, each fluid port associated with a respectivefluid pressure; and a control port in fluid communication with theplurality of fluid ports, and wherein the spool defines: a plurality ofopenings corresponding with the plurality of fluid ports of the sleeveand arranged about the spool to enable selective alignment of a givenopening of the plurality of openings with a given fluid port of theplurality of fluid ports at the given position of the plurality ofpositions; and a control opening in fluid communication with theplurality of openings, and wherein the selective alignment of the givenopening with the given fluid port at the given position allows flow of apressurized fluid at the respective fluid pressure associated with thegiven fluid port through the control opening to the control port. 12.The method of claim 11, wherein actuating the actuator to move the spoolwithin the sleeve to the given position comprises moving the spool tothe given position so that the given opening of the plurality ofopenings partially overlaps the given fluid port of the plurality offluid ports for metering of the pressurized fluid.
 13. The method ofclaim 11, wherein actuating the actuator to move the spool within thesleeve to the given position comprises moving the spool to the givenposition so that the given opening of the plurality of openings overlapsthe given fluid port of the plurality of fluid ports in order to enablesubstantially full alignment between the given opening and the givenfluid port.
 14. The method of claim 11, wherein the plurality ofopenings are configured as through-holes in the spool and arepressure-balanced.
 15. The method of claim 11, wherein the plurality offluid ports have axial widths of substantially equal lengths.
 16. Themethod of claim 15, wherein the plurality of openings have widths ofsubstantially the same lengths as the axial widths of the plurality offluid ports.
 17. The method of claim 11, wherein the plurality of fluidports have axial widths of unequal lengths.
 18. The method of claim 17,wherein the plurality of openings have widths of unequal lengths thatcorrespond to the axial widths of the plurality of fluid ports.
 19. Themethod of claim 11, further comprising: receiving, at the controller, aposition signal from a position sensor configured to sense a position ofthe spool within the sleeve; and determining, by the controller, thelinear movement of the spool based on the position signal from theposition sensor.
 20. The method of claim 11, wherein the sleeve definesa first longitudinal axis and the plurality of ports are spaced apartfrom each other along the longitudinal axis of the sleeve at a firstdistance, and wherein the spool defines a second longitudinal axis andthe plurality of openings are spaced apart from each other along thelongitudinal axis of the spool based on a second distance, the seconddistance based on a fraction of the first distance.